Quote Originally Posted by Jim Becker View Post
Biff, almost all of these spindles, air cooled or water cooled, are three phase which is needed for the variable speed and is also better suited to the task. Traditional routers used by some machines are certainly an exception, but any speed control is manual and done differently than with a spindle. The air requirement isn't necessary for a non ATC spindle other than for a counter-balance on the Z-axis to take load off the steeper or servo from the weight of the spindle. And that's just fixed air pressure...no real "usage". (My machine is so equipped) ATCs, however use air for the quick change mechanism clamping and some use additional air to supplement cooling as has been noted and there is some level of CFM required to support that, not just a particular air pressure as with a counter-balance.
Yea, my spindle in 3 phase as well. That is an additional cost to consider for sure. Plus a lot of extra time to set up the VFD to the correct settings. The main reason I upgraded from a router to a spindle was because I was able to get a lifetime supply of compression bits, but they were "left handed" so I needed to buy a spindle to run them in reverse. If they were still available, I would share the source, but this was years ago. Anyhow, I know this does not apply to most people's situation.

I am lucky that I don't need a counter balance on my Z.. Or if I do need one, it hasn't bitten me yet. But thanks for explaining that, I had no idea what the compressed air was for.

My water cooled spindle worked fine. I am not criticizing anyone for going that way. I should have said.. at the time, given my options, air cooled was much lighter and easier to set up.. your situation might be different.